Androgen receptor in human foreskin. II. Characterization of the receptor from hypospadiac tissue.

Hypospadias represents a spectrum of disorders known as androgen insensitivity syndromes, which are characterized by a nonresponsiveness of an androgen target tissue to the steroid. The basic defect in this disorder is unknown. This article presents results of studies of the androgen receptor with use of human foreskin from normal neonates undergoing circumcision and from patients undergoing urethroplasty necessitated by hypospadias. It is speculated that a defect in receptor level or function might explain this disorder. The androgen receptors from both normal and hypospadiac tissue were stabilized with a buffer containing 50 mM Tris hydrochloride, 1 mM ethylenediaminetetraacetic acid, 12 mM monothioglycerol, 10% (v/v) glycerol, and 10 mM sodium molybdate plus 1 mM phenylmethylsulfonylfluoride (pH 7.5). The receptors were characterized by Scatchard analysis, competitive binding assays, sedimentation analysis, molecular sieve chromatography, and isoelectric focusing techniques. Specific R 1881 binding to soluble proteins from normal human foreskin was shown to be high affinity (dissociation constant = 0.5 nM), low capacity (6 fmol/mg of protein), and steroid specific. Sedimentation analysis by sucrose density gradients demonstrated the 8S-to-4S shift from low- to high-salt treatments. The receptor from the foreskins of hypospadiac patients also contained androgen receptor in a concentration similar to that in the foreskins of normal persons. The affinity for steroid binding and sedimentation profiles or sucrose gradients of the androgen receptor between normal persons and hypospadiac patients were also similar. However, the androgen receptor from hypospadiac patients displayed different patterns of molecular sieve chromatography from those displayed by the receptor of normal persons. The reason for this difference is not known but may reflect a defective receptor and explain the basic mechanism of this disorder.